The present invention relates to a portable terminal device, in particular, it relates to that having a configuration capable of improving the light irregularity at the time of irradiating keys with a light by sectioning a printed board into a portion printed/coated with a high reflector (such as a white ink) and a portion printed/coated with a low reflector (such as a black ink).
FIG. 10 shows an example of arrangement of a key sheet of a conventional portable terminal device. A circuit pattern 2 for electrical connection according to operation of key buttons, and an LED 3 for irradiating the key buttons with a light are provided on the printed board 1. The printed board 1 is applied with a white printing 4 (see the portion marked with slant lines in FIG. 10) except the positions of the circuit pattern 2 and the LED 3. This method has been used commonly as a method for improving the luminance at the time of irradiating keys with a light by applying a white printing 4 on the printed board 1 so as to diffuse the light of the LED 3 disposed on the same surface of the printed board 1.
In this case, since the luminance of the peripheral key buttons are relatively lower with respect to the key buttons disposed in the center array having the LED arranged on the right and the left, the luminance variance (irregularity) is generated when it is viewed as a whole at the time of light irradiation, and thus it is problematic in terms of homogeneity.
As a method for improving the same, conventionally, a method shown in FIGS. 11 and 12 has been practiced. That is, generation of light irregularity has been prevented skillfully by adopting designs of applying the white printing on the rear side of the key buttons close to the LED at the side facing to the key sheet by a larger number of times compared with the other key buttons (see FIG. 11), or by applying the white printing on the entirety of the buttons in the center array, interposed between the LED and applying the white printing only by half of the surface of the peripheral buttons so as to have difference in terms of the light transmissivity (see FIG. 12).
FIG. 13 is a cross-sectional view of a conventional portable terminal device comprising an upper case 5, a lower case 6, a key pad 7, and a printed board 1 with light emitting elements (LED) 3 mounted thereon, applied with the design shown in FIG. 12. It is shown in FIG. 13 that a white printing 4 is applied on a printed board 1, and a white printing is also applied around the key pad buttons for having difference in terms of the light transmissivity so as to prevent generation of light irregularity.
However, since a method of achieving a light weight of buttons by hollowing the rear side of the buttons in various shapes has been used commonly with the recent trend toward a small size and a light weight, a problem arises in that only the portion remained after hollowing can be printed and thus the light irregularity at the time of light irradiation cannot be improved.
Accordingly, an object of the present invention is to provide a portable terminal device for improving the light irregularity at the time of irradiating keys with a light by sectioning a printed board into a portion printed/coated with a high reflector (such as a white ink) and a portion printed/coated with a low reflector (such as a black ink).
A portable terminal device according to the present invention comprises a casing having an upper case and a lower case; a printed board with light emitting elements mounted thereon; and a key pad fit with the upper case, the key pad being translucent, wherein a high reflecting portion and a low reflecting portion are disposed on a part of the printed board.
Since a first aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein a high reflector is printed on the plate surface of a key switch portion of the printed board, and a low reflector is printed on a part thereof, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Moreover, since a second aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein a high reflector is coated on the plate surface of a key switch portion of the printed board, and a low reflector is coated on a part thereof, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Furthermore, since a third aspect of the invention is a portable terminal device comprising an upper case, a lower case, a keypad, and a printed board with light emitting elements mounted thereon, wherein a low reflector is printed on the vicinity of the substantial center of the plate surface of a key switch portion of the printed board lengthwise, and a high reflector is printed on the portion where the low reflector is not printed thereon, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Moreover, since a fourth aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein a low reflector is coated on the vicinity of the substantial center of the plate surface of a key switch portion of the printed board, and a high reflector is coated on the portion where the low reflector is not printed thereon, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Furthermore, since a fifth aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein a high reflector is adhered on the plate surface of a key switch portion of the printed board, and a low reflector is adhered on a part thereof, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Moreover, since a sixth aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein a low reflector is adhered on the vicinity of the substantial center of the plate surface of a key switch portion of the printed board, and a high reflector is adhered on the portion where the low reflector is not printed thereon, the effect of improving the light irregularity at the time of irradiating keys with a light can be achieved.
Moreover, since a seventh aspect of the invention is a portable terminal device comprising an upper case, a lower case, a key pad, and a printed board with light emitting elements mounted thereon, wherein the low reflector is disposed on a portion where an intensity of illumination of the lighting emitting elements is high.
According to the above-mentioned configurations, the light irregularity at the time of irradiating keys with a light can be improved in a portable terminal device with a small size and a light weight.